upgrade.sh is gone

All we do is the bios vendor/version check. We can do that in any case.
Requirements don't change.

We already have a config for a more free version using SeaVGABIOS. From now
on we build, test and release that too. The image filename should just
contail _free_ which is probably enough.

Closes #32

also, we use the check for x230 in the flashing scripts now. They have
to be run as root now.

Now our scripts start with _where_ it should be run. x230_*.sh should
be run on the x230 where Skulls should be installed. external_*.sh
obviously not.

This also adds the -f <flasher> option and an interactive menu if not
specified.

In the future we'll change how our releases look like. This script
is a preliminary outline.